Gyroscopes and accelerometers have been used in many devices over the years, and numerous types, of varying technologies, have been developed. The two most advanced technologies believed to exist are laser based and microelectromechanical systems (MEMS) based. Each of these different technologies, though, has limitations.
An example of a laser based accelerometer is described in U.S. Pat. No. 6,937,432 (“432 patent”). The '432 patent describes a monolithically integrated ring laser gyroscope. Specifically, the light (beams) from two ring lasers is combined through optical couplers so that an interaction of the beams with a photodetector. A problem with this accelerometer is that it is an optical system that requires optical elements to be formed on an integrated circuit (IC) with lasers, photodetectors, and other electronics. Thus, this type of accelerometer can be difficult and expensive to manufacture.
Some other examples of conventional accelerometers are: European Patent No. EP10254221; U.S. Pat. No. 7,030,370; U.S. Pat. No. 4,699,005; U.S. Pat. No. 3,861,220; U.S. Pat. No. 5,383,362; U.S. Pat. No. 5,450,197; U.S. Pat. No. 6,937,342; U.S. Patent Pre-Grant Publ. No. 2006/0105733; and Cao et al., “Large S-Section-Ring-Cavity Diode Lasers: Directional Switching, Electrical Diagnostics, and Mode Beating Spectra” IEEE Photonics Technology Letters, Vol. 17, No. 2, February 2005, pp. 282-284.